In order to properly treat fabric webs, it is often necessary to precisely control air flows in textile treating assemblies. For instance in order to dry and cure finishes of, and to affix dyes to, fabrics, the air flow in tenter ovens must be precisely controlled. Hot air is introduced into the tenter oven through nozzles, usually arranged in an upper plurality of nozzles above the fabric, and a lower plurality of nozzles below the fabric. The heat applied to the fabric is a function of the air velocity through the nozzles, and by controlling the nozzle velocity one can assure equal (or perhaps deliberately unequal and compartmentalized) heat distribution in the oven and uniform treatment across the width of the fabric, as well as uniform treatment of the top and bottom of the fabric.
Conventionally, air distribution control in tenter ovens is determined by a slow and cumbersome process. Each nozzle throughout the oven is individually checked and the data recorded by hand. Should any change be made in the flows within the oven (such as actuation of a damper) each nozzle must again be checked by hand.
According to the present invention a method and apparatus are provided which secure the quick and effective determination of nozzle velocity profiles of a textile treating assembly, and particularly nozzle velocities associated with the nozzles in a tenter oven. Practicing the invention it is possible without arresting the fabric web movement through the tenter oven to progressively and automatically sense the nozzle velocity, and to automatically transmit that information to appropriate instrumentation located exteriorly of the tenter oven so that the information can be readily utilized to properly adjust nozzle velocities (if necessary) to achieve the desired flow characteristics.
Exemplary apparatus according to the invention comprises a web engaging component of a velocity profiling system. The component includes an elongated support having first and second ends with at least one web-engaging pin mounted on the support first end for engaging a portion of the web so that the support moves with the web. An air velocity probe means, such as a pitot tube, is mounted to the support between the first and second ends thereof, and a transducer is operatively connected to the pitot tube for producing electrical signals responsive to the conditions sensed thereby. Electrical connection means extend between the support second end and remote components of the velocity profiling system located exteriorly of the tenter oven. The electrical connection means comprises a wire which is connected to a reeling assembly exterior of the oven, the reeling assembly being substantially that shown and described in U.S. Pat. No. 4,360,277 (the disclosure of which is hereby incorporated by reference herein).
In the method of obtaining the nozzle velocity profile according to the invention, without arresting the fabric web movement the velocity probe--with wire attached--is placed in operative engagement with a specific point of the fabric web as the web moves through the textile treating assembly. The wire is unreeled as the probe moves through the assembly. The velocity is continuously monitored at specific points within the assembly as the fabric moves through the assembly, by monitoring the velocity data supplied by the probe. The probe typically is a pitot tube, and the pressure values sensed thereby are converted to electrical signals and transmitted to the exterior of the textile treating assembly, the velocity being readily calculable from the pressure values sensed. Then without arresting the fabric web movement the probe is disconnected from the web when it exits the textile treating assembly, and the wire is reeled up.
It is the primary object of the present invention to provide a method and apparatus for simply and easily determining nozzle velocities in a textile treating assembly. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.